I use sshfs (FUSE on mac) with a mount point on a small instance that has mounted my S3 bucket. Files get transferred to the server and eventually make it to s3

I use sshfs (FUSE on mac) with a mount point on a small instance that has mounted my S3 bucket. Files get transferred to the server and eventually make it to s3. If you have a little time, you don't need Dropbox at all. And you can't get much cheaper than raw S3.